There are many reasons why couples decide to draft pre or postnuptial agreements: to protect family property and inherited wealth, to address any major change in financial circumstances, or to set out parameters for potential settlement figures if one party's wealth far outweighs that of the other at the outset.

Fear of infidelity may not usually be spoken about openly as a motivation for couples drafting prenuptial and postnuptial agreements, but it is undoubtedly a factor for many who fear the pain, shame and betrayal of having their spouse embark on an extra-marital affair only to be then left with an overriding sense of hurt and a lingering, ineradicable sense of injustice.

It is easy to style any subsequent actions of the wronged party in this circumstance as "revenge" but, perhaps, it should be viewed more simply as the desire to uphold some of the fundamental principles of marriage: respect, partnership and fidelity.

It is no good for a breadwinning partner to cheat on their spouse and then claim that their financial input to the relationship and all that it brings — property, cars, holidays and luxury goods — somehow allows carte blanche, or something approaching it, to disrespect the tenets of monogamy. Provision of wealth in a relationship should not be used as an excuse to disparage an equal partnership between two individuals. Inevitably, at least in the moral universes of the two parties involved, there has to be some consequence for such a breach of the marriage contract.

Increasingly, it would seem, when a spouse strays control is being sought in the legal sphere and the postnuptial agreement allows the aggrieved partner to bring their hurt, injustice and inevitable distrust to the fore. Effectively, this does not mean merely sitting down to renegotiate the original pre-nup contract (in the minds of many cheated-on partners the unfaithful partner has forfeited this right), but instead involves the wronged party laying down some clear rules, which, if adhered to, make the continuation of the relationship possible but, if not, provide a clear template for its termination.

It is easy to see how this might appeal. Under these circumstances the wronged spouse is taking some power back, effectively saying, "Yes, I will stay with you but you have undermined this relationship together with my trust in you so there are going to be a number of important caveats. Cheat on me again and you risk not only losing me but also a far larger share of our shared assets than you would have done previously."

Such a postnuptial agreement serves, like it or not, as a kind of template for justice and it could also be argued that it is in some way an attempt — although not ideologically so — to further redress some of the historical sexual inequality in marriage and divorce law.

A recent Guardian article reported that an increasing number of "betrayed and vengeful wives" are choosing this course. It quoted a family and divorce lawyer as saying his firm had seen a "marked year-on-year rise in terms of the number of clients" it had acted for in these circumstances – "three to four times as many as…five years ago," in fact.

Of course, neither prenuptial agreements nor their postnuptial counterparts are currently legally binding in the family court. However, since a 2008 Privy Council judgment and the 2010 landmark example of German paper company heiress Katrin Radmacher, who won her prenuptial case at the supreme court (her former husband's divorce settlement was reduced from more than £5m to £1m), many have been upheld or at the very least been granted significant weight by courts.

Surely an agreement which places a monetary value on the moral infraction of infidelity is likely to act as significant deterrent to even the most inveterate and shameless of "shaggers".

And it is not only finances that can be affected by these kinds of agreements. Matters that can be addressed include the jurisdiction in which any divorce and financial settlement might be heard and guidance regarding children and other family matters. The former is important. Britain's justice system has repeatedly shown itself to look favourably upon the circumstances of the spouse who makes less money and this helps to explain why pre and postnuptial agreements have become such a popular option, even in a country notorious for its citizens' head-in-sand reticence to planning for divorce or death.

However, some commentators, and even some divorce lawyers, are critical of marital property agreements arguing that they are likely to precipitate the dissolution of marriage, which, goes the argument, is meant to be a sacred and lifelong sacrament. However, in the 21st century it is much easier to give way to reality: we are living longer than ever before and not all marriages will last. Both the prenuptial and the postnuptial agreement recognise this and can serve to help protect spouses, who are at risk of becoming trapped in loveless, lonely or even vaguely abusive existences, from being left at a disadvantage.

It is misguided to imagine that the motivation for such agreements is the sole preserve of the wealth-making party. In relationships where both parties are high earners there often comes a time when one spouse — typically a woman — will give up her career in order to look after children. Prenuptial and postnuptial agreements can help protect against the financial disparity which almost inevitably will then ensue, and ensure that children and homemakers are safeguarded.

Another truth is that people fall in love and sometimes, in this extraordinary meaningful and bonded state, wish to take practical steps to guard against the possibility of their embittered future selves disrespecting the love and bond they felt at the outset. When agreements are drawn up at a time of mutual respect, they can guard against the irrationality and animosity that so often is a feature of separation and divorce. At a time when negative passions and emotions are running amok, returning to an agreement drawn up at a time of calm and respect can be a sobering and affirming experience, and could even change the financial negotiations and outcomes.

So, how can taking the time to understand and place a value upon a marriage do anything other than increase and recognise it both in solemnity and sanctity?

Really and truly, what's not to like about prenuptial and postnuptial agreements? And why should a major blow against a marriage, such as infidelity for example, not prompt spouses to revisit the elements of its constitution. If the drawing up of a contract following a negative event in the relationship can help protect vulnerable parties, and maybe even change the course of the wrong doer's behavior, then surely these are positive results.